Atmospheric factors wind velocity

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

The only model ever published in the literature is poor. The fact, for instance, that burning speed is taken as proportional to wind speed implies that, under calm atmospheric conditions, burning velocities become improbably small, and flash-fire duration proportionately long. The effect of view factors, which change continuously during flame propagation, requires a numerical approach. 

To the extent possible, raising and lowering the mast at the warmest time of the day use any sunlight or predictable atmospheric conditions. Consider the wind velocity factors. 

Concentrations of contaminants in the atmosphere may vary significantly from time to time due to seasonal climatic variation, atmospheric turbulence, and velocity and direction of wind. The most important meteorological factors are (1) wind conditions and the gustiness of wind, (2) the humidity and precipitation, (3) the temperature, which varies with latitude and altitude, (4) barometric pressure (varying with the height above the ground), and (5) solar radiation and the hours of sunshine, which vary with the season. 

We can attempt to apply the same type of model to the H2S data, however there are two additional unknown factors involved. First, we do not have a measurement of the sea surface concentrations of H2S. Second, the piston velocity of H2S is enhanced by a chemical enrichment factor which, in laboratory studies, increases the transfer rate over that expected for the unionized species alone. Balls and Liss (5Q) demonstrated that at seawater pH the HS- present in solution contributes significantly to the total transport of H S across the interface. Since the degree of enrichment is not known under field conditions, we have assumed (as an upper limit) that the transfer occurs as if all of the labile sulfide (including HS ana weakly complexed sulfide) was present as H2S. In this case, the piston velocity of H2S would be the same as that of Radon for a given wind velocity, with a small correction (a factor of 1.14) for the estimated diffusivity difference. If we then specify the piston velocity and OH concentration we could calculate the concentration of H2S in the surface waters. Using the input conditions from model run B from Figure 4a (OH = 5 x 106 molecules/cm3, Vd = 3.1 m/day) yields a sea surface sulfide concentration of approximately 0.1 nM. Figure S illustrates the diurnal profile of atmospheric H2S which results from these calculations. 

The variable emission rates and the meteorological parameters — wind velocity (dilution factor), wind direction (contribution of other sources) and the occurrence of atmospheric wet deposition - are the main parameters responsible for the variation in ambient air concentration levels with a factor of 10. 

There are several factors that contribute to the difficulty of predicting the vertical transport of aerosols. Most obviously, the flow field is not homogeneous in the vertical direction. For neutral atmospheric stability conditions, the mean wind velocity follows an approximately logarithmic velocity profile, given by (Wieringa 1980)... 

The seasonal variations of trace metal composition of atmospheric aerosols are controlled by several meteorological factors such as temperature, humidity and wind velocity and direction. Cold seasons are usually characterized by persistent thermal inversions, high precipitation and low wind velocities which favor the accumulation of anthropogenic exhaust emissions and reduce the presence of road... 

Atmospheric—Atmospheric corrosion is responsible for a large fraction of the total corrosion in the world. Factors that affect the atmospheric corrosion of materials in a marine environment are the time of wetness, temperature, material, atmospheric contaminants and pollutants, solar radiation, composition of the corrosion products, wind velocity, and biological species [fO]. Atmospheric corrosion of a passive alloy tends to be localized. For electrochemical processes related to corrosion to occur, an electrolyte must be present to allow current to pass via diffusion and electrochemical migration of cations and anions. Seawater is a very conductive electrolyte. The severity of corrosion in an atmospheric environment is related to the time of wetness during which electrochemical processes and corrosion take place. There is also a direct relationship between atmospheric salt content and measured corrosion rates [/O]. 

The same factors that promote atmospheric corrosion of metals, time of wetness, atmospheric types, initial exposure conditions, sheltering, wind velocity, and the nature of corrosion products also affect the atmospheric corrosion of ceramics. 

The behavior of aerosol particles in outdoor atmospheres is explained by laws that govern their formation, movement, and capture. These particles are present throughout the planetary boimdary layer and their concentrations depend on a multitude of factors including location, time of day or year, atmospheric conditions, presence of local sources, altitude, and wind velocity. 

The origin of atmospheric turbulence is diurnal heating of the Earth s surface, which gives rise to the convection currents that ultimately drive weather. Differential velocities caused perhaps when the wind encounters an obstacle such as a mountain, result in turbulent flow. The strength of the turbulence depends on a number of factors, including geography it is noted that the best observation sites tend to be the most windward mountaintops of a range— downwind sites experience more severe turbulence caused by the disturbance of those mountains upwind. 

Several laboratory studies have contributed to our understanding of turbulent chemical plumes and the effects of various flow configurations. Fackrell and Robins [25] released an isokinetic neutrally buoyant plume in a wind tunnel at elevated and bed-level locations. Bara et al. [26], Yee et al. [27], Crimaldi and Koseff [28], and Crimaldi et al. [29] studied plumes released in water channels from bed-level and elevated positions. Airborne plumes in atmospheric boundary layers also have been studied in the field by Murlis and Jones [30], Jones [31], Murlis [32], Hanna and Insley [33], Mylne [34, 35], and Yee et al. [36, 37], In addition, aqueous plumes in coastal environments have been studied by Stacey et al. [38] and Fong and Stacey [39], The combined information of these and other studies reveals that the plume structure is influenced by several factors including the bulk velocity, fluid environment, release conditions, bed conditions, flow meander, and surface waves. 

Particle deposition velocities depend on a number of factors, including wind speed, atmospheric stability, relative humidity, particle characteristics (diameter, shape, and density), and receptor surface characteristics. Recent studies on dry particle deposition to surrogate surfaces and derived from atmospheric particle size distributions and micrometeorology suggest that a V equal to about 0.5 cm s 1 is applicable to urban/industrial regions [116-120]. 

The velocity of the wind was found to have a marked effect on the degree of atmospheric pollution, increase in velocity being associated with a decrease in pollution. In the winter, on cloudy days, the pollution, as measured with the Owens automatic air filter, had an average shade of about 1.9 for a velocity of 5 miles per hr, 1.2 for a velocity of about 10 miles, and 0.8 for a velocity of about 20 miles, or when the velocity of the wind doubled, the pollution decreased to about six-tenths of its original value, and when the velocity quadrupled, the pollution decreased to about four-tenths. Wind direction also affected the degree of atmospheric pollution, but this factor depended on local conditions, such as the position of industrial areas, large bodies of water, etc. 

The behaviour of these particles in the air is determined by their chemical and physical characteristics and by their total amount released into the air. Besides these factors, the external atmospheric conditions, particularly the temperature, pressure, humidity, velocity and direction of wind and content of the remaining pollutants are also of importance. 

Under normal conditions, the natural radioactive substances are present in an atomic state in the atmosphere. The natural activity of atmospheric air varies, depending particularly on the content of radioactive substances in the soil and on the intensity of the exchange of substances between the atmosphere and the earth s surface. The process of the release of gases is accelerated in general by an increase of temperature and decrease of the atmospheric pressure. These factors, together with the direction and velocity of the wind, affect the radon concentration in the layer adjacent to the earth s surface and thus also the main source of the natural activity in the atmosphere. 

Variability in bubble populations and dynamics of formation and mass transfer must also contribute to variability in reported gas transfer velocities (for a recent review see [78]). At higher wind speeds, bubbles strongly mediate gas transfer [41, 45, 60, 61]. Bubble populations produced by breaking waves are substantially different in fresh water and seawater [79] and are also likely to vary depending on water temperature, atmospheric pressure, and the presence of surface active matter. Slauenwhite and Johnson [80] found that populations of bubbles produced by break-up of a 5 pi bubble in passage through a small orifice increased by a factor of 3-5 in number in seawater relative to fresh water. They also found that lower temperatures and the presence of natural surface active materials from a diatom bloom significantly enhanced bubble production. 

The dry deposition velocity of particles depends on many factors, such as the size of particles, wind speed, relative humidity and the stability of the surface layer atmosphere. So there are many difficulties in estimating the dry deposition velocity accurately. It is assumed that the dry deposition velocity of nutrient elements is 2.0 cm/s according to the research results. 

Consider the chemical plant example. While the hazard could be defined as death or injury of residents around the plant (the loss event), there may be many factors involved in such a loss that are beyond the control of the plant designers and operators. One example is the atmospheric conditions at the time of the release, such as velocity and direction of the wind. Other factors in a potential accident or loss are the location of humans around the plant and community emergency preparedness, both of which may be under the control of the local or state government. The designers of the chemical plant have a responsibility to provide the information necessary for the design and operation of appropriate emergenq preparedness equipment and procedures, but their primary design responsibility is the part of a potential... 

The cr-values are the standard deviations of the concentration in the direction of the wind, at a right angle from the wind direction and vertically upwards. They can easier be determined experimentally than the eddy coefficient K. The standard deviations depend on the atmospheric conditions and the distance from the source in the direction of the wind. In [26] relationships are given for them which depend on the weather condition (stable, neutral, unstable), the velocity of the wind and the surface roughness Zq (vid. Table 10.5). Separate values for and are provided for Cy the same value as for is used. For distances < 100 m the standard deviations are not verified. That is why results in that range have to be treated with caution. The integration of further factors of influence in the dispersion process is described in [26]. 

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